In recent years, a projection apparatus with a wide angle of view that can perform large screen projection with a short projection distance has been required. In order to realize such a projection apparatus with a wide angle of view, it is effective to adopt a relay-type projection optical system that forms an intermediate image at a time. However, in this case, the total length of the projection optical system is extended, and the projection apparatus main body is also lengthened, so that the effect of shortening the projection distance becomes small. As a countermeasure therefor, a projection optical system with a wide angle of view in which the total length of the projection apparatus main body is shortened by bending a projection light path is proposed in JP 2008-536175 A and JP 2006-523318 A.
Herein, in the relay-type projection optical system, an enlargement-side portion of the intermediate image is set as a first optical system, and a reduction-side portion of the intermediate image is set as a second optical system. In the projection optical system described in JP 2008-536175 A, the light path in the first optical system is bent, and the light path between the first optical system and the second optical system is also bent. Therefore, many optical elements for bending the light path are used, so that cost is increased. In the projection optical system described in JP 2006-523318 A, the light path is not bent in the first optical system, but the light path is bent at the position of the intermediate image. Therefore, in order to shorten the projection optical system in the projection direction, it is necessary to shorten the first optical system for projecting the intermediate image onto the screen, and thus, it is difficult to achieve both of the wide angle of view of the projection and the high image quality of the projected image.